The present invention is directed to an expansion bolt assembly including an anchor bolt and an expansion sleeve with a conically shaped expansion head on one end of the anchor bolt for expanding the expansion sleeve. The anchor bolt has a cylindrical shank extending from the expansion head located at one end toward the opposite end with the diameter of the shank corresponding to the smallest diameter of the expansion head. At the opposite end from the expansion head, means are provided for attaching a load to the anchor bolt.
Expansion bolt assemblies as described above are distinguished by a simple construction and simple installation. By pulling the anchor bolt in the direction opposite to its insertion direction into a borehole, the conically shaped expansion head is moved into the expansion sleeve and, in turn, the sleeve is spread radially outwardly into anchoring contact with the borehole surface.
In a known expansion bolt assembly, means for securing a load to the bolt is provided by a thread formed on the anchor bolt. The region on which the thread is formed is on the outer surface of the cylindrical shank so that the shank extends between the thread and the expansion head on the opposite end of the bolt.
Compared to the nominal diameter of the thread and the tensile strength of the axial region of the bolt on which the thread is formed, the anchor bolt is over-dimensioned. In other words, the anchor bolt requires an unnecessarily high amount of material during fabrication. In addition to the cost of the material forming the bolt, the additional material results in an increased weight of the bolt.